Interior design requires a deep knowledge of human behavior—physical, psychological, and cultural. The ability to understand and communicate with clients is very important. Designed spaces must support the individual lifestyle and functional needs of our clients.
Any interior space directs human behavior. This is especially true for educational, medical, business facilities, or spaces where there is social interaction.
The designer's knowledge of the human factors relating to interior space affects even private spaces, such as residences.

Le Corbusier's Villa Savoye is the epitome of his design theory, “Form follows function”
Sensory Considerations
Consider the sensory considerations of how the principles and elements of design work together with acoustics, lighting, visual stimuli, color theory, scent, and tactile qualities to create a design solution. Special populations including children and the elderly may experience these qualities differently.
Design Theory
Don’t confuse design theory with a design style. Style is an aesthetic, such as French provincial. Design theory is a designer’s unique approach to a creative problem solving process based on one or more of the following:
- Historic precedent
- Human behavior and perception
- A particular process
- Environmental design research and evidence-based design
- A designer’s personal worldview
- Functional needs
Both the elements and principles of design theory are visual building blocks common to all design practices.
Design Theory – Elements
- Form
- Scale
- Color
- Texture
- Pattern
- Light
Design Theory – Principles
- Balance
- Harmony and unity
- Rhythm
- Emphasis/focus
- Contrast and variety
- Proportion
Influences
The design of the built environment relies not only on theory, but also the temperament of what’s happening outside of the immediate confines of the project. While more subjective and ever-changing, some not so obvious influences include:
- Cultural and societal beliefs
- Political conditions
- Cultural symbolism
- Regionalism
- Psychological factors
Economic Factors
Economic conditions frequently resonate in interior and architectural design. In times of financial hardship, designs are often more streamlined and subdued.
A more stable, prosperous economy will often substantiate more luxurious designs.
Ergonomics

Ergonomics studies the relationships between the human body and the physical environment. It uses anthropometric data as a base, but focuses more on the interaction with specific objects and tasks, such as a stove top for cooking or office workstations
Anthropometrics
Anthropometrics focuses on the size, proportion and range of motions of the body.
Findings are statistically grouped by sex, age and percentile ratios.
Proxemics

“Social distance” ranges from 4 to 12 feet and is the distance at which most impersonal business, work and interaction takes place between strangers or in formal situations.
Some behavioral components include proxemics and territoriality.
Proxemics
Describes how people use a space based on circumstance and cultural aspects. Four different distances are identified in the theory of proxemics:
- Intimate distance
- Personal distance
- Social distance
- Public distance
Territoriality
A non-verbal communication in claiming ownership to a space. You've likely seen a person sitting at a six-person sized table at coffee shop with their belongings strewn about, letting others know this is “their space” and their unwillingness to share.

You can pass the NCIDQ Exam.
Join designers like you, and move ahead in your career!